An August 26 article in the New York Times discussed the controversy throughout the country of the use of DNA evidence to possibly exonerate individuals of crimes. The article notes that 130 individuals previously convicted have left prison based on DNA testing which occurred after their convictions at trial. (And we know that many of this group had been on death row.) The second paragraph of the article identifies the substance of the controversy:

Prosecutors acknowledge that DNA testing is reliable, but they have grown increasingly skeptical of its power to prove innocence in cases where there was other evidence of guilt. Defense lawyers say these prosecutors, who often relied on the same biological evidence to convict the defendants before DNA testing was available, are more committed to winning than to justice.

As we consider this issue, we must be reminded that investigatory technique -- particularly in the area of criminal investigations -- is quite sensitive to improvements based on research and technology. For example, research has helped to establish that the traditional "line-up" that we have seen conducted on television "cop" shows for decades is not the most reliable method to ID a perpetrator. Researchers working in laboratories have noted that when a group of five or so individuals are part of a line-up, the real "criminal" is more likely misidentified than if each person is presented to the witness one at a time. Therefore, law enforcement authorities better serve the truth when they use this more recent technique than the one with which we are most familiar.

DNA testing is another area where research and technology have lapped existing practice. Two decades ago using DNA testing to identify physical evidence that could reliably identify the origins of human tissue and fluids did not exist. The police would rely primarily on a victim's or other witness's testimonial evidence to establish identity, or on more primitive forms of forensic evaluation (e.g., matching visible properties of hair; blood typing).

There is an interesting difference between the line-up research and the modern DNA tests. Even though we will acknowledge that a different line-up procedure is now more reliable, we cannot go back and redo the line-up in the original case. We accept that there might be a better procedure now, but we continue to accept even the more reduced reliability of the previous procedure as the then best solution to the problem of identification. By contrast, human genetic material can be tested in a post-trial setting to determine if the jury "got it right." In some cases the testing occurs for the very first time. In others, it might be a retest with a new, more reliable test.

So why would prosecutors resist post-trial testing? The article explores several possible reasons. At one point the author writes:

While prosecutors concede that DNA can prove whether someone is associated with a given piece of biological evidence, they insist that is not the same thing as proving whether a defendant committed a crime.

In the cases of (two Florida inmates), for example, the prosecutors say that the remaining evidence in those cases was strong enough to uphold the men's convictions.

This argument is likely most persuasive when the genetic material tested is taken from a location which is not central to the location of the incident itself. For example, it was in the same room as the victim, but not on the victim. The Florida cases to which the article refers both involve rape. In one the relevant genetic material was found on the woman's bed sheets, and the second on the body of the 11 year old victim. Neither location is so remote from the actual crime as to render a subsequent DNA test irrelevant to deciding whether the jury "got it right."

We're left with the possibility that the prosecutors are married to the jury verdict out of pride. Winning a case is the measure of a prosecutor's success. The trial's result is a reflection of the prosecutor's competence. Now if the case is lost due to incompetent prosecution, then such an assessment is appropriate. But if the case is ultimately won because a prosecutor successfully prevents relevant evidence from emerging, then none of us should approve of that outcome.

Perhaps the most important reflection we can make on a controversy is that the investigative process ought not be the prisoner of an existing decision. If the purpose of the investigation is to learn the truth, then the investigator and those around him or her, must never isolate themselves from new information. In other words, they must remain perpetually objective, even where the previous evidence appeared to justify a conclusion. To reopen a case as a consequence of new or better information that might justify a different conclusion ought be a measure of excellence, not failure.

New York Times citation:

http://www.nytimes.com/2003/08/29/national/29DNA.html?

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